Prius Prime brakes.

The mechanical brakes _are_ used when almost stopped* gradually blending with the regen braking, irrespective of braking pedal pressure.
* Possibly fuzzy memory says under 9 MPH.
As long as you are driving your car, the friction brakes will be used at least some of the time. Certainly enough to keep the rust under control.

 

Except for panic stops. Push the pedal hard enough, and it goes right to friction.

 

The service writers in the dealership are paid only on commission. If they don't write up work, they don't get paid. If they don't write up enough work, they get fired. It's a terrible system. Knowing this, it's shields up! when in every service department.

Brake parts are mainly cast iron. Regions that use a great amount of salt on the winter roads may result in serious brake corrosion. The thin paint or plating on the parts is some help but not perfect. Some lightly used rotors have rusted through from the interior cooling channels from the salt. Brake inspections are important, but they need to be honest. If the service writer can't show why the car needs a $1000 brake job, can't actually defend his report, he's a crook.

When they do inspections require that they list the actual measurements, not just some percentage. Does anyone really think the mechanic measures the pad then divides that by the thickness of a new pad to get the percentage? Or just writes down a quick estimate skewed to give him or his buddies more paid-by-the-job work?

When you bring in a problem, require that the service writer write the problem on the repair order. No fix, no pay. You will pay for the problem to be fixed, not for the service writer's guess of a job that might not fix your problem.

Probably not off a Prime....